High-thermal-conductivity Al-RE-Fe series alloy and preparation method thereof

Abstract

The application discloses a high-thermal-conductivity Al-RE-Fe series alloy and a preparation method thereof, and belongs to the technical field of aluminum-based alloys. The high-thermal-conductivity Al-RE-Fe series alloy comprises the following components in percentage by mass: RE: 8.0-12.0%, Mn: 0.4-0.8%, Cr: 0.01-0.2%, Mg: 0.01-0.3%, Fe: 0.8-1.4%, Zr: 0.1-0.2%, Gd: 0.05-0.5%, Si: 0.02-0.3%, h-BN: 0.05-0.25%, and the balance of Al and inevitable impurities. The h-BN is added in the form of an aluminum-based composite intermediate alloy, can play a pinning role, reduce iron-rich phase tip stress concentration, simultaneously improve the strength and plasticity of the alloy, can simultaneously meet the requirements of brazing and pressure casting forming, and meets the processing and use requirements of liquid cooling runner plate and other thermal management device substrate parts.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-based alloy technology, specifically a high thermal conductivity Al-RE-Fe alloy and its preparation method. Background Technology

[0002] With the development of new energy vehicles, breakthroughs are needed not only in power systems but also higher requirements for the overall vehicle structure and related component materials. Aluminum alloys, with their advantages of lightweight, high strength, and excellent thermal conductivity, are gradually becoming ideal materials in new energy vehicle manufacturing. Furthermore, aluminum alloy die-casting technology, as a highly efficient forming process, is playing an increasingly important role in lightweight design, structural component manufacturing, and thermal management systems for new energy vehicles.

[0003] Thermal management systems are core components of new energy vehicles, such as motors, batteries, and electronic control systems. These systems generate significant heat during high-load and high-power operation, making efficient heat dissipation crucial for ensuring stable system operation. Aluminum alloys possess excellent thermal conductivity, allowing for the manufacture of radiators and heat sinks with complex heat dissipation channel structures. Brazing, as a key method for assembling these components, is suitable for assembling complex liquid cooling systems. However, because brazing is a high-temperature joining process, the traditional approach to ensure the substrate material can withstand the brazing temperature is to use 6-series aluminum profiles (such as 6061 and 6063 aluminum alloys) with high solidus temperatures (≥600℃) combined with CNC machining for manufacturing the thermal management device substrate. However, this aluminum profile + machining method incurs substantial time and material costs.

[0004] Casting offers near-net-shape forming capabilities. If casting could replace the traditional 6-series aluminum profile + CNC machining method, it would significantly reduce the processing time and material costs for thermal management system components. However, most cast aluminum alloys are currently Al-Si or Al-Mg alloys, which have low melting points (<590℃) and cannot withstand high-temperature brazing processes (>600℃). Furthermore, 6-series aluminum alloys, due to their high shrinkage rate and tendency to hot cracking, are unsuitable for die casting.

[0005] To resolve the contradiction between the brazing capability (solidspan temperature > 600℃) and die-casting capability (liquidspan temperature < 660℃) of aluminum alloys, Chinese patent application CN118792551A discloses a high-temperature resistant, brazable, die-cast aluminum alloy. Based on the Al-Mg-Fe system, by controlling the mass ratio of Fe to (Ni+Mn+Cr), excellent die-casting properties, high-temperature resistance, and brazing capability are achieved. Typical mechanical properties include a yield strength of 70-90 MPa, a tensile strength of 170-200 MPa, and an elongation of 10-17%. However, the as-cast yield strength of this alloy is relatively low, failing to meet the requirement of existing thermal management systems for a yield strength ≥ 100 MPa for liquid-cooled flow channel plates. Summary of the Invention

[0006] The purpose of this invention is to provide a high thermal conductivity Al-RE-Fe alloy and its preparation method. Based on an Al-Mg-Fe alloy, rare earth modified boron nitride powder is used as an additive phase. Combined with element control, the mechanical strength and thermal conductivity of the alloy are improved. This solves the problems of difficulty in controlling the iron-rich phase and insufficient yield strength in high-iron content die-cast alloys, and meets the comprehensive requirements of high thermal conductivity and weldability for related die-cast components of thermal management systems.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A high thermal conductivity Al-RE-Fe alloy comprises the following components by mass percentage:

[0009] RE: 8.0-12.0%, Mn: 0.4-0.8%, Cr: 0.01-0.2%, Mg: 0.01-0.3%, Fe: 0.8-1.4%, Zr: 0.1-0.2%, Gd: 0.05-0.5%, Si: 0.02-0.3%, h-BN: 0.05-0.25%, balance being Al and unavoidable impurities.

[0010] RE is at least one of La and Ce.

[0011] Furthermore, h-BN is added in the form of an aluminum-based composite master alloy, which is prepared through the following steps:

[0012] Step 1: Add hexagonal boron nitride nanosheets and 90-110 mL of deionized water to a flask and stir to mix. Disperse by sonication for 4-5 h. Then add a 5 mol / L sodium hydroxide solution to the flask and mix. Stir at 80-85℃ and 150-200 r / min for 10-12 h. Place the resulting dispersion in a 120℃ oven for 10-12 h and allow it to cool naturally to room temperature. Filter the solution and wash the precipitate with deionized water until the final wash solution is neutral. Dry the precipitate under vacuum at 60-80℃ to constant weight to obtain alkali-treated hexagonal boron nitride nanosheets.

[0013] The ratio of hexagonal boron nitride nanosheets to sodium hydroxide solution is 10g:180-220mL.

[0014] Step 2: Dissolve rare earth nitrates in deionized water to obtain a rare earth nitrate solution with a molar concentration of 0.5 mol / L; add alkali-treated hexagonal boron nitride nanosheets and the rare earth nitrate solution to a reaction vessel, stir for 30 min at 60℃ and 200-300 r / min, then add mixed alkali solution dropwise to the reaction vessel until the pH value is 9, stop the dropwise addition and continue stirring for 2-3 h, then age at 20-25℃ for 10-12 h, centrifuge the reaction solution at 8000 r / min for 5-10 min, wash the precipitate with deionized water by centrifugation 3-5 times, and vacuum dry at 60-80℃ to constant weight to obtain modified boron nitride precursor powder.

[0015] The ratio of alkali-treated hexagonal boron nitride nanosheets to rare earth nitrate solution is 1 g: 100 mL.

[0016] The mixed alkaline solution is prepared by mixing sodium carbonate, sodium hydroxide and deionized water in a ratio of 0.3 mol: 1 mol: 1 L.

[0017] Rare earth nitrates are lanthanum nitrate hexahydrate or cerium nitrate hexahydrate.

[0018] Step 3: Transfer the modified boron nitride precursor powder to a crucible and place it in a tube furnace. Hold it at 500-550℃ in an air atmosphere for 3-3.5 hours, and then allow it to cool naturally to room temperature to obtain rare earth modified boron nitride powder. Mix the rare earth modified boron nitride powder, pure gadolinium powder, and pure aluminum powder by ball milling under an argon atmosphere. Transfer the resulting mixed powder to a spark plasma hot pressing sintering furnace and sinter it for 4-5 minutes under argon protection, at 500℃ and 50MPa to obtain an aluminum-based composite master alloy containing nano boron nitride.

[0019] Rare earth modified boron nitride powder accounts for 3-5 wt% of the mixed powder, and pure gadolinium powder accounts for 0.5-1 wt% of the mixed powder.

[0020] This invention also provides a high thermal conductivity Al-RE-Fe alloy and its preparation method, which is prepared through the following steps:

[0021] Pure aluminum ingots are added to an electric resistance melting furnace and completely melted at 700-720℃. The temperature is then raised to 750-800℃, and rare earth aluminum alloys and aluminum-zirconium alloys are added. After complete melting, the temperature is lowered to 720-750℃, and aluminum-manganese alloys, aluminum-chromium alloys, aluminum-silicon alloys, and aluminum-iron alloys are added. After complete melting, a rotary jetting device is used to inject N2 containing 0.3-2% refining agent by weight of the melt for powder refining, degassing, and slag removal. After slag removal, the melt is cooled to 700-720℃, and pure magnesium ingots, aluminum-based composite master alloys, and aluminum-gadolinium alloys are added. The pure magnesium ingots are completely pressed into the bottom of the melting furnace and fully melted. Stir the melt and let it stand for 25-30 minutes. Perform pre-furnace composition analysis on the melt to detect the composition content of the alloy melt. For melts with deviations in content, add material or dilute to bring the composition to the designed Al-RE-Fe alloy composition range. Heat the melt to 720-730℃, set the graphite rotor speed to 150-200 r / min, and spray refining gas at a gas flow rate of 1-1.5 L / min to degas for 8-10 minutes. Let it stand for 10-15 minutes, remove the slag, and then perform high-pressure casting on the melt. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0022] Rare earth aluminum alloys are at least one of aluminum-lanthanum alloys and aluminum-cerium alloys.

[0023] During the powder spraying refining process, the graphite rotor speed of the rotary jetting device is 450-550 r / min, the degassing and deslag removal time is 5-10 min, the gas source pressure during degassing is 0.35±0.05 MPa, and the gas flow rate is 10-20 L / min. The melt is then allowed to stand for 5-10 min.

[0024] The refining gas is an Ar / N2 mixture with a volume fraction of 50%.

[0025] The high-pressure casting temperature is 690-750℃, the casting pressure is 80-120MPa, the injection speed is 1.5-3m / s, and the mold used for high-pressure casting is the die-casting test rod mold.

[0026] The beneficial effects of this invention are:

[0027] 1. The high thermal conductivity Al-RE-Fe alloy of this invention can simultaneously meet the requirements of brazing and die casting. It can be die cast in one step by high pressure casting and has mechanical properties with a yield strength of ≥100MPa in a heat treatment-free state. It can replace the traditional "aluminum profile + CNC" processing mode, reduce material and manufacturing costs, and meet the processing and use requirements of thermal management device substrate parts such as liquid cooling flow channel plates.

[0028] 2. The high thermal conductivity Al-RE-Fe alloy of this invention contains h-BN, which acts as a pinning agent, helping to refine the alloy grains and regulate the morphology of the iron-rich phase, reducing the aspect ratio of the acicular phase, thereby reducing stress concentration at the tips and simultaneously improving the strength and plasticity of the alloy. h-BN is added in the form of an aluminum-based composite master alloy. During the preparation of the aluminum-based composite master alloy, the hexagonal boron nitride nanosheet raw material is first alkali-treated to improve the surface activity of the hexagonal boron nitride nanosheets, which helps rare earth ions form a coating layer on their surface through co-precipitation. After calcination, rare earth oxide nanoclusters are formed, releasing active rare earth atoms during the preparation of the aluminum-based composite master alloy, improving the interfacial wettability between h-BN and aluminum. Gadolinium acts as an interfacial activator, thereby improving the wettability between the h-BN additive phase and the aluminum melt, reducing agglomeration, and achieving the effect of enhancing the thermal conductivity and mechanical properties of the alloy.

[0029] 3. The high thermal conductivity Al-RE-Fe alloy of this invention contains trace amounts of chromium (Cr) and gadolinium (Gd). Chromium is dissolved in trace amounts (0.08-0.18 wt%) in the iron-rich intermetallic compound. The difference in atomic radius between chromium and iron / aluminum leads to lattice distortion of the iron-rich phase, increasing the energy barrier required for its anisotropic growth and inhibiting the rapid expansion of the acicular phase along its long axis. This reduces the influence of the iron-rich phase on the alloy and helps to regulate the mechanical properties and thermal conductivity of the alloy. Gadolinium plays a role in regulating the activity of grain boundaries and phase interfaces. Its addition is strictly controlled within the trace range of 0.2-0.5 wt%. Through grain boundary segregation and interfacial reactions, it alleviates the problem of thermal expansion coefficient mismatch between h-BN and the aluminum matrix, contributing to improved plasticity and weldability of the alloy. Attached Figure Description

[0030] Figure 1 The image shows the metallographic structure of the Al-RE-Fe alloy in Example 4 of this invention under a 200x microscope.

[0031] Figure 2 This is a metallographic image of the Al-RE-Fe alloy in Comparative Example 1 of this invention under a 200x microscope;

[0032] Figure 3 This is a metallographic image of the Al-RE-Fe alloy in Comparative Example 2 of this invention under a 200x microscope;

[0033] Figure 4 Metallographic image of the Al-RE-Fe alloy in Comparative Example 3 of this invention under a 200x microscope;

[0034] Figure 5 The image shows the metallographic structure of the Al-RE-Fe alloy in Comparative Example 4 of this invention under a 200x microscope.

[0035] Figure 6 Metallographic image of the Al-RE-Fe alloy in Comparative Example 5 of this invention under a 200x microscope;

[0036] Figure 7 The image shows the metallographic structure of the Al-RE-Fe alloy in Comparative Example 6 of this invention under a 200x microscope. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1: This example provides an aluminum-based composite master alloy containing nano-boron nitride, which is prepared through the following steps:

[0039] Step 1: Add 10g of hexagonal boron nitride nanosheets and 90mL of deionized water to a flask and stir to mix. Disperse by sonication for 4h. Then add 180mL of 5mol / L sodium hydroxide solution to the flask and mix. Stir at 80℃ and 150r / min for 10h. Place the resulting dispersion in a 120℃ oven for 10h and allow it to cool naturally to room temperature. Filter the solution and wash the precipitate with deionized water until the final wash solution is neutral. Dry the precipitate under vacuum at 60℃ to constant weight to obtain alkali-treated hexagonal boron nitride nanosheets.

[0040] Step 2: Dissolve cerium nitrate hexahydrate (i.e., rare earth nitrate) in deionized water to obtain a lanthanum nitrate solution with a molar concentration of 0.5 mol / L; add 5 g of alkali-treated hexagonal boron nitride nanosheets and 500 mL of cerium nitrate solution to the reaction vessel, stir for 30 min at 60 °C and 200 r / min, then add a mixed alkali solution dropwise to the reaction vessel until the pH value is 9 (the mixed alkali solution is prepared by mixing sodium carbonate, sodium hydroxide and deionized water in a ratio of 0.3 mol: 1 mol: 1 L), stop the dropwise addition and continue stirring for 2 h, then age at 20 °C for 10 h, centrifuge the reaction solution at 8000 r / min for 5 min, wash the precipitate three times with deionized water by centrifugation, and vacuum dry at 60 °C to constant weight to obtain modified boron nitride precursor powder.

[0041] Step 3: Transfer 5g of modified boron nitride precursor powder to a crucible and place it in a tube furnace. Hold it at 500℃ in an air atmosphere for 3 hours, and then let it cool naturally to room temperature to obtain rare earth modified boron nitride powder. Mix 3g of rare earth modified boron nitride powder, 0.5g of pure gadolinium powder and 96.5g of pure aluminum powder by ball milling under argon protection. Then transfer the mixed powder to a spark plasma hot pressing sintering furnace and sinter it for 4 minutes under argon protection, 500℃ and 50MPa to obtain an aluminum-based composite master alloy containing nano boron nitride.

[0042] Example 2: This example provides an aluminum-based composite master alloy containing nano-boron nitride, which is prepared through the following steps:

[0043] Step 1: Add 10g of hexagonal boron nitride nanosheets and 100mL of deionized water to a flask and stir to mix. Disperse by sonication for 4.5h. Then add 200mL of 5mol / L sodium hydroxide solution to the flask and mix. Stir at 85℃ and 180r / min for 11h. Place the resulting dispersion in a 120℃ oven for 11h and allow it to cool naturally to room temperature. Filter the solution and wash the precipitate with deionized water until the final wash solution is neutral. Dry the precipitate under vacuum at 70℃ to constant weight to obtain alkali-treated hexagonal boron nitride nanosheets.

[0044] Step 2: Dissolve cerium nitrate hexahydrate (i.e., rare earth nitrate) in deionized water to obtain a lanthanum nitrate solution with a molar concentration of 0.5 mol / L; add 5 g of alkali-treated hexagonal boron nitride nanosheets and 500 mL of cerium nitrate solution to the reaction vessel, stir for 30 min at 60 °C and 250 r / min, then add a mixed alkali solution dropwise to the reaction vessel until the pH value is 9 (the mixed alkali solution is prepared by mixing sodium carbonate, sodium hydroxide and deionized water in a volume ratio of 0.3 mol: 1 mol: 1 L), stop the dropwise addition and continue stirring for 2.5 h, then age at 25 °C for 11 h, centrifuge the reaction solution at 8000 r / min for 8 min, wash the precipitate four times with deionized water by centrifugation, and vacuum dry at 70 °C to constant weight to obtain modified boron nitride precursor powder.

[0045] Step 3: Transfer 5g of modified boron nitride precursor powder to a crucible and place it in a tube furnace. Hold the mixture at 520℃ in an air atmosphere for 3.2h, and allow it to cool naturally to room temperature to obtain rare earth modified boron nitride powder. Mix 4g of rare earth modified boron nitride powder, 0.8g of pure gadolinium powder, and 95.2g of pure aluminum powder by ball milling under argon protection. Then, transfer the mixed powder to a spark plasma hot pressing sintering furnace and sinter it for 4.5min under argon protection, 500℃, and 50MPa to obtain an aluminum-based composite master alloy containing nano boron nitride.

[0046] Example 3: This example provides an aluminum-based composite master alloy containing nano-boron nitride, which is prepared through the following steps:

[0047] Step 1: Add 10g of hexagonal boron nitride nanosheets and 110mL of deionized water to a flask and stir to mix. Disperse by sonication for 5h. Then add 220mL of 5mol / L sodium hydroxide solution to the flask and mix. Stir at 85℃ and 200r / min for 12h. Place the resulting dispersion in a 120℃ oven for 12h and allow it to cool naturally to room temperature. Filter the solution and wash the precipitate with deionized water until the final wash solution is neutral. Dry the precipitate under vacuum at 80℃ to constant weight to obtain alkali-treated hexagonal boron nitride nanosheets.

[0048] Step 2: Dissolve cerium nitrate hexahydrate (i.e., rare earth nitrate) in deionized water to obtain a lanthanum nitrate solution with a molar concentration of 0.5 mol / L; add 5 g of alkali-treated hexagonal boron nitride nanosheets and 500 mL of cerium nitrate solution to the reaction vessel, stir for 30 min at 60 °C and 300 r / min, then add a mixed alkali solution dropwise to the reaction vessel until the pH value is 9 (the mixed alkali solution is prepared by mixing sodium carbonate, sodium hydroxide and deionized water in a ratio of 0.3 mol: 1 mol: 1 L), stop the dropwise addition and continue stirring for 3 h, then age at 20 °C for 12 h, centrifuge the reaction solution at 8000 r / min for 10 min, wash the precipitate five times with deionized water by centrifugation, and vacuum dry at 80 °C to constant weight to obtain modified boron nitride precursor powder.

[0049] Step 3: Transfer 5g of modified boron nitride precursor powder to a crucible and place it in a tube furnace. Hold it at 550℃ in an air atmosphere for 3.5h, and then let it cool naturally to room temperature to obtain rare earth modified boron nitride powder. Mix 5g of rare earth modified boron nitride powder, 1g of pure gadolinium powder and 94g of pure aluminum powder by ball milling under argon protection. Then transfer the mixed powder to a spark plasma hot pressing sintering furnace and sinter it for 5min under argon protection, 500℃ and 50MPa to obtain an aluminum-based composite master alloy containing nano boron nitride.

[0050] Example 4: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0051] Pure aluminum ingots were added to a resistance melting furnace and completely melted at 710°C. The temperature was then raised to 770°C, and aluminum-lanthanum alloy, aluminum-cerium alloy, and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 735°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 1% of the total weight of the melt as a refining agent for powder spraying refining, degassing, and degassing treatment. During the powder spraying refining, degassing, and degassing treatment, the graphite rotor speed of the rotary jetting device was 500 r / min, the degassing and deslag removal time was 7 min, the gas source pressure was 0.35 MPa, and the gas flow rate was 15 L / min. The melt was then allowed to stand for 8 min, and after slag removal, the melt was cooled to 710°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 1, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely pressed... The melt is placed at the bottom of the melting furnace and thoroughly stirred after complete melting. It is then allowed to stand for 25 minutes for melting. The melt is then subjected to pre-furnace composition analysis to detect the composition content of the alloy melt. Melts with deviations in content are replenished or diluted to bring the composition to the designed Al-RE-Fe alloy composition range. The melt is then heated to 725℃, and the graphite rotor speed is set to 180 r / min. Refining gas (50% Ar / N2 mixture by volume) is injected at a gas flow rate of 1.2 L / min. After degassing for 9 minutes and standing for 12 minutes, the melt is then subjected to high-pressure casting at a temperature of 730℃, a casting pressure of 100 MPa, and an injection speed of 2 m / s. The mold used for high-pressure casting is a die-casting test rod mold. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0052] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0053] RE (La: 5%, Ce: 5%), Mn: 0.6%, Cr: 0.1%, Mg: 0.15%, Fe: 1.1%, Zr: 0.15%, Gd: 0.3%, Si: 0.15%, h-BN: 0.15%, balance Al and unavoidable impurities.

[0054] Metallographic image of the high thermal conductivity Al-RE-Fe alloy under a 200x microscope is shown below. Figure 1 As shown, its grains are fine and uniformly distributed, with no obvious needle-like or plate-like β-Al5FeSi phase.

[0055] Example 5: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0056] Pure aluminum ingots were added to an electric resistance melting furnace and completely melted at 700°C. The temperature was then raised to 750°C, and aluminum-lanthanum alloy, aluminum-cerium alloy, and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 720°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 0.3% of the total melt weight of refining agent into the melt for powder refining, degassing, and deslag removal. During the powder refining, deslag removal, and degassing treatment, the graphite rotor speed of the rotary jetting device was 450 r / min, the degassing and deslag removal time was 5 min, the gas source pressure was 0.3 MPa, and the gas flow rate was 10 L / min. The melt was then allowed to stand for 5 min, and after slag removal, the melt was cooled to 700°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 2, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely melted. The melt is pressed into the bottom of the melting furnace and thoroughly stirred after complete melting. It is then allowed to stand for 25 minutes for melting. The melt is then subjected to pre-furnace composition analysis to detect the composition content of the alloy melt. Melts with deviations in content are replenished or diluted to bring the composition to the designed Al-RE-Fe alloy composition range. The melt is then heated to 720℃, and the graphite rotor speed is set to 150 r / min. Refining gas (50% Ar / N2 mixture by volume) is injected at a gas flow rate of 1 L / min. After degassing for 8 minutes and standing for 10 minutes, the melt is then subjected to high-pressure casting at a temperature of 690℃, a casting pressure of 85 MPa, and an injection speed of 1.5 m / s. The mold used for high-pressure casting is a die-casting test rod mold. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0057] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0058] RE (La: 7%, Ce: 3.5%), Mn: 0.55%, Cr: 0.15%, Mg: 0.11%, Fe: 0.8%, Zr: 0.11%, Gd: 0.42%, Si: 0.17%, h-BN: 0.1%, balance Al and unavoidable impurities.

[0059] Example 6: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0060] Pure aluminum ingots were added to a resistance melting furnace and completely melted at 720°C. The temperature was then raised to 800°C, and aluminum-lanthanum alloy, aluminum-cerium alloy, and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 740°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 1.7% of the total melt weight of refining agent into the melt for powder spraying refining, degassing, and degassing treatment. During the powder spraying refining, degassing, and degassing treatment, the graphite rotor speed of the rotary jetting device was 480 r / min, the degassing and deslag removal time was 9 min, the gas source pressure was 0.36 MPa, and the gas flow rate was 11 L / min. The melt was then allowed to stand for 10 min, and after slag removal, the melt was cooled to 715°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 3, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely pressed... The melt is placed at the bottom of the melting furnace and thoroughly stirred after complete melting. It is then allowed to stand for 30 minutes for melting. The melt is then subjected to pre-furnace composition analysis to detect the composition content of the alloy melt. Melts with deviations in content are replenished or diluted to bring the composition to the designed Al-RE-Fe alloy composition range. The melt is then heated to 730℃, and the graphite rotor speed is set to 200 r / min. Refining gas (50% Ar / N2 mixture by volume) is injected at a gas flow rate of 1.5 L / min. After degassing for 10 minutes and standing for 15 minutes, the melt is subjected to high-pressure casting at a temperature of 745℃, a casting pressure of 105 MPa, and an injection speed of 2.2 m / s. The mold used for high-pressure casting is a die-casting test rod mold. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0061] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0062] RE (La: 2.1%, Ce: 9.5%), Mn: 0.67%, Cr: 0.09%, Mg: 0.04%, Fe: 1%, Zr: 0.13%, Gd: 0.23%, Si: 0.02%, h-BN: 0.2%, balance Al and unavoidable impurities.

[0063] Example 7: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0064] Pure aluminum ingots were added to an electric resistance melting furnace and completely melted at 720°C. The temperature was then raised to 755°C, and aluminum-lanthanum alloy, aluminum-cerium alloy, and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 750°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 2.0% of the total melt weight of refining agent into the melt for powder spraying refining, degassing, and deslag removal. During the powder spraying refining, deslag removal, and degassing treatment, the graphite rotor speed of the rotary jetting device was 5300 r / min, the degassing and deslag removal time was 8 min, the gas source pressure was 0.34 MPa, and the gas flow rate was 17 L / min. The melt was then allowed to stand for 7 min, and after slag removal, the melt was cooled to 720°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 1, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely melted. The melt is pressed into the bottom of the melting furnace and thoroughly stirred after complete melting. It is then allowed to stand for 28 minutes for melting. The melt is then subjected to pre-furnace composition analysis to detect the composition content of the alloy melt. Melts with deviations in content are replenished or diluted to bring the composition to the designed Al-RE-Fe alloy composition range. The melt is then heated to 725℃, and the graphite rotor speed is set to 190 r / min. Refining gas (50% Ar / N2 mixture by volume) is injected at a gas flow rate of 1.4 L / min. After degassing for 9 minutes and standing for 13 minutes, the melt is subjected to high-pressure casting at a temperature of 750℃, a casting pressure of 95 MPa, and an injection speed of 2.4 m / s. The mold used for high-pressure casting is a die-casting test rod mold. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0065] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0066] RE (La: 5.3%, Ce: 6.7%), Mn: 0.4%, Cr: 0.12%, Mg: 0.16%, Fe: 1.25%, Zr: 0.18%, Gd: 0.33%, Si: 0.3%, h-BN: 0.15%, balance Al and unavoidable impurities.

[0067] Example 8: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0068] Pure aluminum ingots were added to a resistance melting furnace and completely melted at 700°C. The temperature was then raised to 765°C, and aluminum-lanthanum alloy and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 725°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 0.7% of the total melt weight of refining agent into the melt for powder spraying refining, degassing, and degassing treatment. During the powder spraying refining, degassing, and degassing treatment, the graphite rotor speed of the rotary jetting device was 520 r / min, the degassing and deslag removal time was 10 min, the gas source pressure was 0.32 MPa, and the gas flow rate was 13 L / min. The melt was then allowed to stand for 9 min, and after slag removal, the melt was cooled to 705°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 2, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely pressed into the furnace. At the bottom of the melting furnace, after complete melting, the melt is thoroughly stirred and allowed to stand for 28 minutes. A pre-furnace composition analysis is performed on the melt to determine the alloy composition content. Melts with deviations in content are replenished or diluted to bring the composition within the designed Al-RE-Fe alloy range. The melt is then heated to 721℃, and the graphite rotor speed is set to 160 r / min. Refining gas (50% Ar / N2 mixture by volume) is injected at a flow rate of 1.2 L / min. Degassing is performed for 8 minutes, followed by standing for 10 minutes. After slag removal, the melt is subjected to high-pressure casting at a temperature of 710℃, a casting pressure of 115 MPa, and an injection speed of 3 m / s. A die-casting test rod mold is used for high-pressure casting. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0069] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0070] RE (La: 8.4%), Mn: 0.52%, Cr: 0.06%, Mg: 0.01%, Fe: 1.15%, Zr: 0.1%, Gd: 0.47%, Si: 0.04%, h-BN: 0.08%, balance Al and unavoidable impurities.

[0071] Example 9: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0072] Pure aluminum ingots were added to an electric resistance melting furnace and completely melted at 720°C. The temperature was then raised to 780°C, and aluminum-lanthanum alloy, aluminum-cerium alloy, and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 745°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 1.1% of the total melt weight of refining agent into the melt for powder refining, degassing, and deslag removal. During the powder refining, deslag removal, and degassing treatment, the graphite rotor speed of the rotary jetting device was 470 r / min, the degassing and deslag removal time was 6 min, the gas source pressure was 0.38 MPa, and the gas flow rate was 15 L / min. The melt was then allowed to stand for 6 min, and after slag removal, the melt was cooled to 710°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 3, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely pressed... The melt is placed at the bottom of the melting furnace and thoroughly stirred after complete melting. It is then allowed to stand for 28 minutes for melting. The melt is then subjected to pre-furnace composition analysis to detect the composition content of the alloy melt. Melts with deviations in content are replenished or diluted to bring the composition to the designed Al-RE-Fe alloy composition range. The melt is then heated to 723℃, and the graphite rotor speed is set to 190 r / min. Refining gas (50% Ar / N2 mixture by volume) is injected at a gas flow rate of 1.3 L / min. After degassing for 10 minutes and standing for 14 minutes, the melt is subjected to high-pressure casting at a temperature of 700℃, a casting pressure of 100 MPa, and an injection speed of 1.9 m / s. The mold used for high-pressure casting is a die-casting test rod mold. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0073] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0074] RE (La: 4.6%, Ce: 4.9%), Mn: 0.74%, Cr: 0.2%, Mg: 0.08%, Fe: 1.4%, Zr: 0.14%, Gd: 0.5%, Si: 0.28%, h-BN: 0.22%, balance Al and unavoidable impurities.

[0075] Example 10: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0076] Pure aluminum ingots were added to a resistance melting furnace and completely melted at 720°C. The temperature was then raised to 790°C, and aluminum-lanthanum alloy, aluminum-cerium alloy, and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 730°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 1.5% of the total melt weight of refining agent into the melt for powder spraying refining, degassing, and degassing treatment. During the powder spraying refining, degassing, and degassing treatment, the graphite rotor speed of the rotary jetting device was 550 r / min, the degassing and deslag removal time was 7 min, the gas source pressure was 0.37 MPa, and the gas flow rate was 18 L / min. The melt was then allowed to stand for 10 min, and after slag removal, the melt was cooled to 720°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 2, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely pressed... The melt is placed at the bottom of the melting furnace and thoroughly stirred after complete melting. It is then allowed to stand for 30 minutes for melting. The melt is then subjected to pre-furnace composition analysis to detect the composition content of the alloy melt. Melts with deviations in content are replenished or diluted to bring the composition to the designed Al-RE-Fe alloy composition range. The melt is then heated to 726℃, and the graphite rotor speed is set to 190 r / min. Refining gas (50% Ar / N2 mixture by volume) is injected at a gas flow rate of 1.4 L / min. After degassing for 10 minutes and standing for 15 minutes, the melt is subjected to high-pressure casting at a temperature of 695℃, a casting pressure of 110 MPa, and an injection speed of 2.3 m / s. The mold used for high-pressure casting is a die-casting test rod mold. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0077] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0078] RE (La: 6.7%, Ce: 1.3%), Mn: 0.8%, Cr: 0.14%, Mg: 0.19%, Fe: 0.9%, Zr: 0.12%, Gd: 0.16%, Si: 0.06%, h-BN: 0.12%, balance Al and unavoidable impurities.

[0079] Example 11: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0080] Pure aluminum ingots were added to an electric resistance melting furnace and completely melted at 720°C. The temperature was then raised to 750°C, and aluminum-cerium alloy and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 725°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 0.9% of the total melt weight of refining agent into the melt for powder spraying refining, degassing, and degassing treatment. During the powder spraying refining, degassing, and degassing treatment, the graphite rotor speed of the rotary jetting device was 540 r / min, the degassing and deslag removal time was 5 min, the gas source pressure was 0.39 MPa, and the gas flow rate was 19 L / min. The melt was then allowed to stand for 5 min, and after slag removal, the melt was cooled to 710°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 1, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely pressed into the melt. At the bottom of the furnace, after complete melting, the melt is thoroughly stirred and allowed to stand for 27 minutes. A pre-furnace composition analysis is performed on the melt to determine its alloy composition content. Melts with deviations in content are replenished or diluted to bring the composition within the designed Al-RE-Fe alloy range. The melt is then heated to 720°C, and a graphite rotor speed of 150 r / min is set. Refining gas (50% Ar / N2 mixture by volume) is injected at a flow rate of 1.2 L / min. Degassing is performed for 8 minutes, followed by standing for 10 minutes. After slag removal, the melt is subjected to high-pressure casting at 720°C, a casting pressure of 120 MPa, and an injection speed of 2.8 m / s. A die-casting test mold is used for high-pressure casting. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0081] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0082] RE (Ce: 9.7%), Mn: 0.61%, Cr: 0.07%, Mg: 0.2%, Fe: 0.85%, Zr: 0.16%, Gd: 0.26%, Si: 0.11%, h-BN: 0.18%, balance Al and unavoidable impurities.

[0083] Example 12: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0084] Pure aluminum ingots were added to an electric resistance melting furnace and completely melted at 710°C. The temperature was then raised to 785°C, and aluminum-lanthanum alloy, aluminum-cerium alloy, and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 730°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 1.2% of the total melt weight of refining agent into the melt for powder refining, degassing, and deslag removal. During the powder refining, degassing, and degassing treatment, the graphite rotor speed of the rotary jetting device was 510 r / min, the degassing and deslag removal time was 9 min, the gas source pressure was 0.4 MPa, and the gas flow rate was 12 L / min. The melt was then allowed to stand for 10 min, and after slag removal, the melt was cooled to 700°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 3, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely melted. The melt is pressed into the bottom of the melting furnace and thoroughly stirred after complete melting. It is then allowed to stand for 25 minutes for melting. The melt is then subjected to pre-furnace composition analysis to detect the composition content of the alloy melt. Melts with deviations in content are replenished or diluted to bring the composition to the designed Al-RE-Fe alloy composition range. The melt is then heated to 727°C, and the graphite rotor speed is set to 190 r / min. Refining gas (50% Ar / N2 mixture by volume) is injected at a gas flow rate of 1.3 L / min. After degassing for 9 minutes and standing for 14 minutes, the melt is then subjected to high-pressure casting at a temperature of 705°C, a casting pressure of 90 MPa, and an injection speed of 2.5 m / s. The mold used for high-pressure casting is a die-casting test rod mold. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0085] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0086] RE (La: 3.1%, Ce: 7.2%), Mn: 0.42%, Cr: 0.16%, Mg: 0.27%, Fe: 1.2%, Zr: 0.2%, Gd: 0.05%, Si: 0.25%, h-BN: 0.25%, balance Al and unavoidable impurities.

[0087] Example 13: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0088] Pure aluminum ingots were added to an electric resistance melting furnace and completely melted at 705°C. The temperature was then raised to 760°C, and aluminum-lanthanum alloy, aluminum-cerium alloy, and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 740°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 0.4% of the total melt weight of refining agent into the melt for powder spraying refining, degassing, and degassing treatment. During the powder spraying refining, degassing, and degassing treatment, the graphite rotor speed of the rotary jetting device was 460 r / min, the degassing and deslag removal time was 8 min, the gas source pressure was 0.35 MPa, and the gas flow rate was 14 L / min. The melt was then allowed to stand for 7 min, and after slag removal, the melt was cooled to 715°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 1, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely pressed... The melt is placed at the bottom of the melting furnace and thoroughly stirred after complete melting. It is then allowed to stand for 28 minutes for melting. The melt is then subjected to pre-furnace composition analysis to detect the composition content of the alloy melt. Melts with deviations in content are replenished or diluted to bring the composition to the designed Al-RE-Fe alloy composition range. The melt is then heated to 730℃, and the graphite rotor speed is set to 200 r / min. Refining gas (50% Ar / N2 mixture by volume) is injected at a gas flow rate of 1.5 L / min. After degassing for 10 minutes and standing for 10 minutes, the melt is then subjected to high-pressure casting at a temperature of 715℃, a casting pressure of 115 MPa, and an injection speed of 2.6 m / s. The mold used for high-pressure casting is a die-casting test rod mold. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0089] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0090] RE (La: 0.8%, Ce: 8.1%), Mn: 0.76%, Cr: 0.013%, Mg: 0.05%, Fe: 1.35%, Zr: 0.19%, Gd: 0.39%, Si: 0.09%, h-BN: 0.05%, balance Al and unavoidable impurities.

[0091] Example 14: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0092] Pure aluminum ingots were added to an electric resistance melting furnace and completely melted at 715°C. The temperature was then raised to 795°C, and aluminum-lanthanum alloy, aluminum-cerium alloy, and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 750°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 1.6% of the total melt weight of refining agent into the melt for powder refining, degassing, and deslag removal. During the powder refining, degassing, and degassing treatment, the graphite rotor speed of the rotary jetting device was 490 r / min, the degassing and deslag removal time was 10 min, the gas source pressure was 0.33 MPa, and the gas flow rate was 16 L / min. The melt was then allowed to stand for 9 min, and after slag removal, the melt was cooled to 720°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 2, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely melted. The melt is pressed into the bottom of the melting furnace and thoroughly stirred after complete melting. It is then allowed to stand for 30 minutes for melting. The melt is then subjected to pre-furnace composition analysis to detect the composition content of the alloy melt. Melts with deviations in content are replenished or diluted to bring the composition to the designed Al-RE-Fe alloy composition range. The melt is then heated to 730℃, and the graphite rotor speed is set to 180 r / min. Refining gas (50% Ar / N2 mixture by volume) is injected at a gas flow rate of 1.2 L / min. After degassing for 8 minutes and standing for 10 minutes, the melt is subjected to high-pressure casting at a temperature of 735℃, a casting pressure of 80 MPa, and an injection speed of 1.7 m / s. The mold used for high-pressure casting is a die-casting test rod mold. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0093] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0094] RE (La: 8.7%, Ce: 0.5%), Mn: 0.49%, Cr: 0.18%, Mg: 0.22%, Fe: 0.95%, Zr: 0.17%, Gd: 0.08%, Si: 0.16%, h-BN: 0.15%, balance Al and unavoidable impurities.

[0095] Example 15: This example provides a method for preparing a high thermal conductivity Al-RE-Fe alloy. The steps of the preparation method are as follows:

[0096] Pure aluminum ingots were added to an electric resistance melting furnace and completely melted at 710°C. The temperature was then raised to 775°C, and aluminum-lanthanum alloy, aluminum-cerium alloy, and aluminum-zirconium alloy were added. After complete melting, the temperature was lowered to 735°C, and aluminum-manganese alloy, aluminum-chromium alloy, aluminum-silicon alloy, and aluminum-iron alloy were added. After complete melting, a rotary jetting device was used to inject N2 containing 1.8% of the total melt weight of refining agent into the melt for powder spraying refining, degassing, and degassing treatment. During the powder spraying refining, degassing, and degassing treatment, the graphite rotor speed of the rotary jetting device was 500 r / min, the degassing and deslag removal time was 6 min, the gas source pressure was 0.32 MPa, and the gas flow rate was 15 L / min. The melt was then allowed to stand for 6 min, and after slag removal, the melt was cooled to 705°C. Pure magnesium ingots, the aluminum-based composite master alloy from Example 1, and aluminum-gadolinium alloy were added, and the pure magnesium ingots were completely melted. The melt is pressed into the bottom of the melting furnace and thoroughly stirred after complete melting. It is then allowed to stand for 25 minutes for melting. The melt is then subjected to pre-furnace composition analysis to detect the composition content of the alloy melt. Melts with deviations in content are replenished or diluted to bring the composition to the designed Al-RE-Fe alloy composition range. The melt is then heated to 729°C, and the graphite rotor speed is set to 190 r / min. Refining gas (50% Ar / N2 mixture by volume) is injected at a gas flow rate of 1.3 L / min. After degassing for 9 minutes and standing for 12 minutes, the melt is then subjected to high-pressure casting at a temperature of 725°C, a casting pressure of 95 MPa, and an injection speed of 1.8 m / s. The mold used for high-pressure casting is a die-casting test rod mold. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained.

[0097] The composition of this high thermal conductivity Al-RE-Fe alloy, by mass percentage, is as follows:

[0098] RE (La: 1.2%, Ce: 10.1%), Mn: 0.58%, Cr: 0.01%, Mg: 0.3%, Fe: 1.3%, Zr: 0.15%, Gd: 0.11%, Si: 0.21%, h-BN: 0.2%, balance Al and unavoidable impurities.

[0099] The aluminum-lanthanum alloy used in the examples is designated as Al-20La, the aluminum-cerium alloy as Al-20Ce, the aluminum-zirconium alloy as Al-10Zr, the aluminum-manganese alloy as Al-10Mn, the aluminum-chromium alloy as Al-10Cr, the aluminum-silicon alloy as Al-20Si, the aluminum-iron alloy as Al-20Fe, and the aluminum-gadolinium alloy as Al-10Gd. All alloys were preheated to 200°C and dried before being added.

[0100] The hexagonal boron nitride nanosheets used in the examples were purchased from Zhenhan New Materials (Suzhou) Co., Ltd., item number ZH-HBN-073-1, with an average particle size of 100nm; the pure gadolinium powder with a particle size of 100nm was purchased from Changsha Xinkang New Materials Co., Ltd.; the refining agent was Siyuan brand smokeless refining agent, purchased from Xuzhou Siyuan Aluminum Co., Ltd.

[0101] Comparative Example 1: The difference from the examples is that no aluminum-based composite master alloy was added during the preparation process. The final Al-RE-Fe alloy composition by mass percentage is shown below:

[0102] RE (La: 5%, Ce: 5%), Mn: 0.6%, Cr: 0.1%, Mg: 0.15%, Fe: 1.1%, Zr: 0.15%, Gd: 0.3%, Si: 0.15%, balance Al and unavoidable impurities.

[0103] Metallographic image of the high thermal conductivity Al-RE-Fe alloy under a 200x microscope is shown below. Figure 2 As shown, its grains are significantly coarsened, with many rod-shaped and needle-shaped iron-rich phases appearing, and obvious pores appearing at the grain boundary junctions.

[0104] Comparative Example 2: The difference from Example 4 is that, instead of adding the basic composite master alloy prepared in Example 1, an aluminum-based composite master alloy prepared in the following steps is added:

[0105] Step 1: Add 10g of hexagonal boron nitride nanosheets and 90mL of deionized water to a flask and stir to mix. Disperse by sonication for 4h. Then add 180mL of 5mol / L sodium hydroxide solution to the flask and mix. Stir at 80℃ and 150r / min for 10h. Place the resulting dispersion in a 120℃ oven for 10h and allow it to cool naturally to room temperature. Filter the solution and wash the precipitate with deionized water until the final wash solution is neutral. Dry the precipitate under vacuum at 60℃ to constant weight to obtain alkali-treated hexagonal boron nitride nanosheets.

[0106] Step 2: 3g of alkali-treated hexagonal boron nitride nanosheets, 0.5g of pure gadolinium powder and 96.5g of pure aluminum powder are ball-milled and mixed under argon protection. The mixed powder is then transferred to a spark plasma hot pressing sintering furnace and sintered at 500℃ and 50MPa for 4min to obtain an aluminum-based composite master alloy containing nano-boron nitride.

[0107] The final composition of the Al-RE-Fe alloy, by mass percentage, is shown below:

[0108] RE (La: 5%, Ce: 5%), Mn: 0.6%, Cr: 0.1%, Mg: 0.15%, Fe: 1.1%, Zr: 0.15%, Gd: 0.3%, Si: 0.15%, h-BN: 0.15%, balance Al and unavoidable impurities.

[0109] Metallographic image of the high thermal conductivity Al-RE-Fe alloy under a 200x microscope is shown below. Figure 3 As shown, irregular gray-black agglomerates appear between the grain boundaries, which may be h-BN micron-sized agglomerates.

[0110] Comparative Example 3: The difference from Example 4 is that no aluminum-gadolinium alloy was added during the preparation process. The final composition of the Al-RE-Fe alloy by mass percentage is shown below:

[0111] RE (La: 5%, Ce: 5%), Mn: 0.6%, Cr: 0.1%, Mg: 0.15%, Fe: 1.1%, Zr: 0.15%, Si: 0.15%, h-BN: 0.15%, balance Al and unavoidable impurities.

[0112] Metallographic image of the high thermal conductivity Al-RE-Fe alloy under a 200x microscope is shown below. Figure 2 As shown, its grain boundaries are relatively coarse, and dark-colored brittle phases can be seen deposited at the grain boundaries.

[0113] Comparative Example 4: The difference from Example 4 is that the amount of aluminum-gadolinium alloy added during the preparation process was increased. The final composition of the Al-RE-Fe alloy by mass percentage is shown below:

[0114] RE (La: 5%, Ce: 5%), Mn: 0.6%, Cr: 0.1%, Mg: 0.15%, Fe: 1.1%, Zr: 0.15%, Gd: 1%, Si: 0.15%, h-BN: 0.15%, balance Al and unavoidable impurities.

[0115] Metallographic image of the high thermal conductivity Al-RE-Fe alloy under a 200x microscope is shown below. Figure 3 As shown, in addition to the iron-rich phase, massive or short needle-like brittle GdAl3 phases can be seen between dendrites or at the junctions of grain boundaries.

[0116] Comparative Example 5: The difference from Example 4 is that no aluminum-chromium alloy was added during the preparation process. The final composition of the Al-RE-Fe alloy by mass percentage is shown below:

[0117] RE (La: 5%, Ce: 5%), Mn: 0.6%, Mg: 0.15%, Fe: 1.1%, Zr: 0.15%, Gd: 0.3%, Si: 0.15%, h-BN: 0.15%, balance Al and unavoidable impurities.

[0118] Metallographic image of the high thermal conductivity Al-RE-Fe alloy under a 200x microscope is shown below. Figure 4 As shown, coarse needle-like and plate-like β-Al5FeSi phases appear between grain boundaries, forming a "skeleton-like" brittle network.

[0119] Comparative Example 6: The difference from Example 4 is that the amount of aluminum-chromium alloy added during the preparation process was increased. The final composition of the Al-RE-Fe alloy by mass percentage is shown below:

[0120] RE (La: 5%, Ce: 5%), Mn: 0.6%, Cr: 0.5%, Mg: 0.15%, Fe: 1.1%, Zr: 0.15%, Gd: 0.3%, Si: 0.15%, h-BN: 0.15%, balance Al and unavoidable impurities.

[0121] Metallographic image of the high thermal conductivity Al-RE-Fe alloy under a 200x microscope is shown below. Figure 5 As shown, its tissue uniformity is acceptable, but the dark spots may be due to the aggregation of the brittle CrAl7 phase.

[0122] The mass percentage composition of each Al-RE-Fe alloy in Examples 4-15 and Comparative Examples 1-6 is shown in Table 1:

[0123] Table 1. Mass percentage composition of various Al-RE-Fe alloys

[0124] project La / % Ce / % Mn / % Cr / % Mg / % Fe / % Zr / % Gd / % Si / % h-BN / % Al / % Example 4 5.0 5.0 0.6 0.1 0.15 1.1 0.15 0.3 0.15 0.15 margin Example 5 7.0 3.5 0.55 0.15 0.11 0.8 0.11 0.42 0.17 0.1 margin Example 6 2.1 9.5 0.67 0.09 0.04 1.0 0.13 0.23 0.02 0.2 margin Example 7 5.3 6.7 0.4 0.12 0.16 1.25 0.18 0.33 0.3 0.15 margin Example 8 8.4 0 0.52 0.06 0.01 1.15 0.1 0.47 0.04 0.08 margin Example 9 4.6 4.9 0.74 0.2 0.08 1.4 0.14 0.5 0.28 0.22 margin Example 10 6.7 1.3 0.8 0.14 0.19 0.9 0.12 0.16 0.06 0.12 margin Example 11 0 9.7 0.61 0.07 0.2 0.85 0.16 0.26 0.11 0.18 margin Example 12 3.1 7.2 0.42 0.16 0.27 1.2 0.2 0.05 0.25 0.25 margin Example 13 0.8 8.1 0.76 0.013 0.05 1.35 0.19 0.39 0.09 0.05 margin Example 14 8.7 0.5 0.49 0.18 0.22 0.95 0.17 0.08 0.16 0.15 margin Example 15 1.2 10.1 0.58 0.01 0.3 1.3 0.15 0.11 0.21 0.2 margin Comparative Example 1 5.0 5.0 0.6 0.1 0.15 1.1 0.15 0.3 0.15 0 margin Comparative Example 2 5.0 5.0 0.6 0.1 0.15 1.1 0.15 0.3 0.15 0.15 margin Comparative Example 3 5.0 5.0 0.6 0.1 0.15 1.1 0.15 0 0.15 0.15 margin Comparative Example 4 5.0 5.0 0.6 0.1 0.15 1.1 0.15 1.0 0.15 0.15 margin Comparative Example 5 5.0 5.0 0.6 0 0.15 1.1 0.15 0.3 0.15 0.15 margin Comparative Example 6 5.0 5.0 0.6 0.5 0.15 1.1 0.15 0.3 0.15 0.15 margin

[0125] The high thermal conductivity Al-RE-Fe alloy die-cast test bars (16 mm wide, 4 mm thick, 100 mm long, conforming to the Type A tensile test specimen standard in GB / T 13822-2017) in the examples and comparative examples were tested for yield strength, tensile strength and elongation according to GB / T 228.1-2021. Each die-cast test bar was cut in the middle and then welded using laser-arc hybrid welding. The shape and specifications were the same as the original die-cast test bar. The power of laser-arc hybrid welding was 5.5 kW, the welding speed was 0.1 m / s, ER4043 welding wire was used, the wire feed speed was 9 m / min, the wire spacing was 3 mm, and the defocusing amount was -3 mm. After welding, the tensile strength of the welded joint was tested, and the welding coefficient was calculated. The larger the welding coefficient, the better the weldability of the alloy. The welding coefficient = tensile strength of welded joint / original tensile strength.

[0126] In the high-pressure casting process of each embodiment and comparative example, the mold was replaced with a disc mold to prepare disc samples (diameter of 12.7 mm and thickness of 3 mm). The thermal conductivity of each disc sample at 20 °C was tested in accordance with GB / T 22588-2022.

[0127] The relevant experimental results are shown in Table 2:

[0128] Table 2. Test results of various Al-RE-Fe alloys

[0129] project Yield strength / MPa Tensile strength / MPa Elongation / % Welding coefficient Thermal conductivity / W / m·K Example 4 108 227 6.9 0.93 191.5 Example 5 101 214 7 0.91 199.6 Example 6 105 207 6.3 0.9 193.1 Example 7 111 214 5.4 0.92 190.2 Example 8 107 220 5.4 0.91 188.5 Example 9 115 240 4.9 0.89 186.8 Example 10 102 194 6.1 0.88 192.3 Example 11 101 204 5.8 0.92 194.5 Example 12 108 213 6.4 0.87 182.6 Example 13 113 227 4.3 0.88 181.5 Example 14 103 222 6.2 0.86 185.4 Example 15 114 241 4.4 0.85 181.2 Comparative Example 1 95 200 4.8 0.78 162.5 Comparative Example 2 105 215 6.2 0.88 185.2 Comparative Example 3 98 214 4.2 0.85 183.8 Comparative Example 4 108 218 5.8 0.82 183.1 Comparative Example 5 92 204 5.5 0.84 169.4 Comparative Example 6 102 208 3.7 0.8 174.8

[0130] As shown in Table 2, the Al-RE-Fe alloy prepared in the examples exhibits high yield strength, tensile strength, elongation, weldability, and thermal conductivity. Without heat treatment after high-pressure casting, a yield strength of ≥100 MPa can be obtained, and the strength of the laser-arc hybrid welded joint reaches more than 85% of the base material.

[0131] Comparative Example 1, which did not contain h-BN, lacked grain refinement and thermal conductivity enhancement effects, resulting in the lowest thermal conductivity, decreased yield strength, and deformation of the die-cast test bar after baking at 600℃. This indicates that rare earth modified boron nitride powder is key to improving the thermal conductivity, mechanical properties, and weldability of the alloy.

[0132] The decrease in relevant performance in Comparative Example 2 compared to Example 4 is due to the uneven dispersion of unmodified h-BN in the aluminum melt, which makes it prone to agglomeration and floating.

[0133] In Comparative Example 3 and Comparative Example 4, both thermal conductivity and elongation decreased, indicating that when Gd was added in trace amounts, the alloy maintained high strength while achieving excellent plastic deformation capacity and weld joint reliability. At the same time, the precise addition of trace amounts of Gd is the key to achieving the synergy of high weldability and high thermal conductivity; excessive addition, on the contrary, will induce the negative effect of brittle phase.

[0134] Comparative Examples 5 and 6 show that trace amounts of Cr are an irreplaceable element for achieving the synergistic effect of "high Fe content alloying" and "high thermal conductivity + high strength", while excessive Cr leads to ductile collapse dominated by brittle phase.

[0135] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0136] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A high thermal conductivity Al-RE-Fe alloy, characterized in that, This high thermal conductivity Al-RE-Fe alloy comprises the following components by mass percentage: RE: 8.0-12.0%, Mn: 0.4-0.8%, Cr: 0.01-0.2%, Mg: 0.01-0.3%, Fe: 0.8-1.4%, Zr: 0.1-0.2%, Gd: 0.05-0.5%, Si: 0.02-0.3%, h-BN: 0.05-0.25%, balance being Al and unavoidable impurities; The RE is at least one of La and Ce.

2. The high thermal conductivity Al-RE-Fe alloy according to claim 1, characterized in that, The h-BN is added in the form of an aluminum-based composite master alloy, which is prepared through the following steps: The modified boron nitride precursor powder was transferred to a crucible and placed in a tube furnace. It was held at 500-550℃ in an air atmosphere for 3-3.5 hours and then naturally cooled to room temperature to obtain rare earth modified boron nitride powder. The rare earth modified boron nitride powder, pure gadolinium powder and pure aluminum powder were ball-milled and mixed in an argon atmosphere. The resulting mixed powder was transferred to a spark plasma hot pressing sintering furnace and sintered for 4-5 minutes under argon protection, 500℃ and 50MPa to obtain an aluminum-based composite master alloy containing nano boron nitride.

3. The high thermal conductivity Al-RE-Fe alloy according to claim 2, characterized in that, The rare earth modified boron nitride powder accounts for 3-5 wt% of the mixed powder, and the pure gadolinium powder accounts for 0.5-1 wt% of the mixed powder.

4. The high thermal conductivity Al-RE-Fe alloy according to claim 2, characterized in that, The modified boron nitride precursor powder is prepared by the following steps: Rare earth nitrates were dissolved in deionized water to obtain a rare earth nitrate solution with a molar concentration of 0.5 mol / L. Alkali-treated hexagonal boron nitride nanosheets and the rare earth nitrate solution were added to a reaction vessel and stirred at 60℃ and 200-300 r / min for 30 min. Then, mixed alkali solution was added dropwise until the pH value was 9. The dropwise addition was stopped and stirring was continued for 2-3 h. The mixture was then aged at 20-25℃ for 10-12 h. The reaction solution was centrifuged at 8000 r / min for 5-10 min. The precipitate was washed 3-5 times with deionized water by centrifugation and then vacuum dried at 60-80℃ to constant weight to obtain modified boron nitride precursor powder.

5. A high thermal conductivity Al-RE-Fe alloy according to claim 4, characterized in that, The ratio of the amount of alkaline-treated hexagonal boron nitride nanosheets to rare earth nitrate solution is 1g:200mL; The mixed alkaline solution is prepared by mixing sodium carbonate, sodium hydroxide and deionized water in a ratio of 0.3 mol: 1 mol: 1 L. The rare earth nitrate is lanthanum nitrate hexahydrate or cerium nitrate hexahydrate.

6. A high thermal conductivity Al-RE-Fe alloy according to claim 4, characterized in that, The alkali-treated hexagonal boron nitride nanosheets are prepared by the following steps: Hexagonal boron nitride nanosheets and 90-110 mL of deionized water were added to a flask and stirred. The mixture was ultrasonically dispersed for 4-5 h. Then, a 5 mol / L sodium hydroxide solution was added to the flask and stirred at 80-85 °C and 150-200 r / min for 10-12 h. The resulting dispersion was placed in a 120 °C oven and kept warm for 10-12 h. After naturally cooling to room temperature, the mixture was filtered. The precipitate was washed with deionized water until the final wash was neutral. The precipitate was then vacuum dried at 60-80 °C to constant weight to obtain alkali-treated hexagonal boron nitride nanosheets. The ratio of hexagonal boron nitride nanosheets to sodium hydroxide solution is 10g:180-220mL.

7. The method for preparing a high thermal conductivity Al-RE-Fe alloy according to claim 1, characterized in that, Includes the following steps: Pure aluminum ingots are added to an electric resistance melting furnace and completely melted at 700-720℃. The temperature is then raised to 750-800℃, and rare earth aluminum alloys and aluminum-zirconium alloys are added. After complete melting, the temperature is lowered to 720-750℃, and aluminum-manganese alloys, aluminum-chromium alloys, aluminum-silicon alloys, and aluminum-iron alloys are added. After complete melting, a rotary jetting device is used to inject N2 containing 0.3-2% refining agent by weight of the melt for powder refining, degassing, and slag removal. After slag removal, the melt is cooled to 700-720℃, and pure magnesium ingots, aluminum-based composite master alloys, and aluminum-gadolinium alloys are added. The pure magnesium ingots are completely pressed into the bottom of the melting furnace and fully melted. Stir the melt and let it stand for 25-30 minutes. Perform pre-furnace composition analysis on the melt to detect the composition content of the alloy melt. For melts with deviations in content, add material or dilute to bring the composition to the designed Al-RE-Fe alloy composition range. Heat the melt to 720-730℃, set the graphite rotor speed to 150-200 r / min, and spray refining gas at a gas flow rate of 1-1.5 L / min to degas for 8-10 minutes. Let it stand for 10-15 minutes, remove the slag, and then perform high-pressure casting on the melt. After casting, a high thermal conductivity Al-RE-Fe alloy is obtained. The rare earth aluminum alloy is at least one of aluminum-lanthanum alloy and aluminum-cerium alloy.

8. The method for preparing a high thermal conductivity Al-RE-Fe alloy according to claim 7, characterized in that, During the powder spraying refining slag removal and degassing treatment, the graphite rotor speed of the rotary blowing device is 450-550 r / min, the degassing and slag removal time is 5-10 min, the gas source pressure during degassing is 0.35±0.05 MPa, the gas flow rate is 10-20 L / min, and then the melt is allowed to stand for 5-10 min.

9. The method for preparing a high thermal conductivity Al-RE-Fe alloy according to claim 7, characterized in that, The refining gas is an Ar / N2 mixture with a volume fraction of 50%.

10. The method for preparing a high thermal conductivity Al-RE-Fe alloy according to claim 7, characterized in that, The high-pressure casting temperature is 690-750℃, the casting pressure is 80-120MPa, and the injection speed is 1.5-3m / s.

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